Integrated lead or wireless suspensions and flexures (i.e., suspension components) are used to support read/write transducers in disk drives or other dynamic data storage systems. These devices typically have a stainless steel or other spring metal layer for supporting the electrical traces. A layer of dielectric insulating material separates the traces from the stainless steel.
Electrical connections between otherwise isolated conductors on suspension assemblies (e.g., between the conductor and stainless steel layers) can be created by applying a conductive epoxy material into a via or through hole extending through at least some of the layers. This interconnect can be formed using a screen printing process. The conductive epoxy material provides an acceptable connection in some applications, for example, ground applications. Creating a good connection between the epoxy material and the stainless steel surface of the suspension assembly, however, has proven to be difficult because the stainless steel surface often has an adhered layer of oxidation on its surface, which prevents a good electrical connection.
Printed circuit boards used in electronic assemblies often have more than one level of electric conductors separated by an insulative material such as fiberglass. Plated vias or through holes connect the conductors on different layers. The plating process used to plate vias or through holes involves metalizing the dielectric inside the holes using an electroless process and then electroplating on top of the electroless to create conductivity between the conductor layers through the via or through hole.
Unfortunately, the circuit board interconnect process does not work well for a suspension assembly because the metal applied using the electroless process does not adhere well to the stainless steel material on the suspension assembly. The electroless process, therefore, tends to create undesirable particulate. The process is also relatively expensive.
There is, therefore, a need for an effective method of applying conductive material to a suspension assembly to provide a reliable connection between two conductive surfaces that are otherwise isolated from each other. Any such method must be capable of producing high-quality electrical contacts. It should also be efficient to manufacture.